The present invention relates to a fire protection and safety glazing laminate including high modulus layers and fluoropolymer resin layers wherein the fluoropolymer resin layer resides between the high modulus layers. The fluoropolymer resin layer is surface treated and corona treated in an organic gas atmosphere such that the fluoropolymer resin layer adheres to the high modulus layers without benefit of adhesive or other tie layers.
Protective glazing laminates are used in many interior and exterior building applications. Protective laminates are usually constructed with at least one polymeric interlayer film sandwiched between at least two structural supports made of mineral or polymer glass or polymeric substrates. Currently a variety of materials are used for different applications. Those interlayer materials may include polyvinyl butyral (PVB), ethylene vinyl acetate copolymers (EVA), polycarbonate (PC), ionomeric resins, metallocene polyethylene m-LLDPE and/or fluoropolymers. The films are usually laminated to the substrate through heat and pressure. In addition, many materials require an adhesion primer, either incorporated into the film formulation as an additive or coated on the surface substrates. In many cases the films are also given a raised pattern on their surface to improve lamination through a better air removal process, prior to bonding the polymer layer to the substrate.
In applications where fire resistance is a requirement, it is necessary to choose an interlayer material that will retain its structure at high temperatures and not degrade to potentially harmful fumes when burned. Another function of the adhesive interlayer is to prevent the structure from losing glass debris, after the laminate has been exposed to the high heat of fire. Very few materials, besides fluoropolymers, will be able to meet this criteria. Due to its highly electronegative structure and its high surface energy, fluoropolymers do not bond well to other materials. When using fluoropolymers it is necessary to use an effective priming step to increase the bondability of the material to the glass substrate. The priming step can tend to be messy, time consuming and may decrease the fire resistance of the interlayer materials, due to the organic nature of most of the primers.
Surface (corona) treatment of materials is a common method to improve adhesion to typical substrates. In the case of fluoropolymer resin layers, however, the treatment will only last in the range of minutes to hours. Corona treatment using an organic atmosphere, hereinafter, C-Treatment (where the C refers to the Cementability of the film after treatment), has been proven to give superior adhesion to substrates that will last an extended time, on the order of months to years. The C-Treatment of fluoropolymer resin layers will enhance their adhesion to glass, however, the adhesion may not be not strong enough to pass the rigorous impact tests specified by the building industry for safety and fire protective glazing.
U.S. Pat. No. 5,230,954 (Sakamoto et al., Jul. 27, 1993) relates to a fire protective glass panel for use in a fire protective window, door and partition wall, which comprises at least one sheet of fireproof glass plate and a fluorocarbon resin film of a chain molecular structure type bonded to a side surface of the glass plate and which has non-shattering property as well as fire protection property wherein the fireproof glass plate is a heat-resistant and light transparent crystallized glass plate or, alternatively, the fireproof glass plate is a wire glass plate and the fluorocarbon resin film has a thickness of 0.02-1 mm and is made of one of FEP, PFA, PCTFE, ETFE and PVDF
U.S. Pat. No. 5,529,655 (Bravet et al., Jun. 25, 1996) relates to a laminated safety pane, comprising a monolithic or laminated substrate of glass and/or of plastics material and a sheet of plastics material comprising at least one external polyurethane film providing desirable surface properties. According to the reference, the pane is provided, on at least one zone of the polyurethane film, with a gluing prefilm compatible with a film of adhesive deposited later, this prefilm being deposited after an electrical treatment applied to at least the zone of the polyurethane film which is to receive the prefilm, this electrical treatment being chosen from among the treatments of the corona discharge type.
U.S. Pat. No. 5,624,761 (Sakamoto et al., Apr. 29, 1997) is directed to a fire-protection and safety composite glass panel that includes a fireproof glass plate and a film of fluorocarbon resin of a chain molecular structure type. The film is bonded onto one of opposite side surfaces of the fireproof glass plate by the thermo-compression bonding. The fluorocarbon resin is a copolymer of at least three kinds of monomers. It may be arranged that another film of the fluorocarbon resin is further bonded onto the other side surface of the fireproof glass plate by the thermo-compression bonding. Another glass panel may be arranged that a plurality of fireproof glass plates are attached with a film of the foregoing fluorocarbon resin interposed between adjacent glass plates through the thermo-compression bonding. Those glass panels can be used as glass plates in fire protective windows and doors.
U.S. Pat. No. 5,908,704 (Friedman et al., Jun. 1, 1999) relates to optical and firescreening protective glazing laminates comprising fluoropolymer interlayer films. The films and their laminates comprise THV and blends of THV with FEP, ECTFE or ECCTFE and modified with additives, such as coupling agents, pigment or color concentrates, and IR- or UV-light blockers, and may be subjected to a surface corona treatment. The films also may incorporate a fiber mesh for additional reinforcement.
U.S. Pat. No. 5,972,176 (Kirk et al., Oct. 26, 1999) describes a process for corona treating a polymer. The process involves exposing at least one surface of an article comprising a polymeric material selected from the group consisting of fluoropolymers, polycarbonates, and polyimides to a corona discharge in an atmosphere containing nitrogen and about 0.01 to about 10 percent of an additional gas selected from the group consisting of hydrogen, ammonia and mixtures thereof.
U.S. Pat. No. 6,042,928 (Suzuki et al., Mar. 28, 2000) describes a fluorocarbon resin sheet having a fluorine content of at least 55 percent and a melting point of from 60 to 220xc2x0 C., made solely of a polymer comprising at least one fluorine-containing monomer, or made of a blend of such a polymer with other polymer, which has a total light transmittance of at least 80% and a tensile modulus of elasticity within a range of from 1xc3x97107 to 4xc3x97109 Pa within an entire measuring temperature range of from 0 to 30xc2x0 C., wherein the surface of the resin sheet is embossed to have a center line average roughness Ra of from 0.05 to 2.0 xcexcm and a number of peaks Pc of from 5 to 500 peaks/8 mm.
In many of the references discussed above, a separate adhesive layer is necessary for adhesion of the interlayer to the glass substrates. Often this layer must be specially made or treated to reduce its flammability in fire resistant glazing. It is the object of this invention to show that a combination of surface patterning (either raised line or random matte pattern) and a C-Treatment of a fluoropolymer resin layer or layers in an organic gas environment, will serve to significantly improve the adhesion of the fluoropolymer resin layer or layers to high modulus layers without the need for priming of their surface or addition of a flammable adhesive layer.
Disclosed is a fire-protection and safety glazing laminate having a haze value less than 4 percent comprising
(A) a plurality of high modulus layers laminated with
(B) at least one fluoropolymer resin layer
wherein (B) resides between (A),
wherein the high modulus layers comprise glass, polycarbonate or polyurethane,
wherein the fluoropolymer resin layer has a matte finish surface, an embossed finish surface or a combination thereof,
wherein the fluoropolymer resin layer is exposed to a corona treatment in an organic gas atmosphere and
wherein the high modulus layers are adhered to the fluoropolymer resin layer through a pressure and heat lamination.